The design of current third generation (3G), and enhanced 3G, wireless access networks is driven by the need for high speed internet access. Increasingly, consumers are moving to wireless communications for the delivery of services and applications using conventional TCP/IP (Transmission Control Protocol/Internet Protocol), or other packet-based protocols. This trend is growing with the increase in internet-enabled wireless devices available to users, including cellular telephones, Personal Digital Assistants (PDAs), and other devices. The applications that are now available, or contemplated, for wireless devices include access to services such as the World Wide Web, video telephony, voice over IP and e-mail, etc.
Current wireless access networks, both second generation (2G) and 3G systems, are connection-oriented designs. In 2G systems, a physical connection, or radio link, is set up between a wireless terminal, mobile or fixed, and the network by a simple call setup procedure. Such a call setup procedure includes information exchange, or authentication, and resource allocation, or channel assignment, for both the forward link and the reverse link. After this call setup procedure, the resources allocated are dedicated to the user until the call is released. Any traffic received by the terminal on the dedicated forward link channel belongs to this terminal. Any traffic received by the network on the dedicated reverse link is from the terminal. Such connection-oriented design is suitable to stream type of applications, such as voice, video and audio. However, for internet packet applications, significant resources are wasted due to the characteristically high burstyness of packet applications.
In order to increase the efficiency of resource utilization, current 3G systems, such as those developed under the cdma2000 1xRTT standard and the Universal Mobile Telecommunications System (UMTS), can provide resource sharing on forward link supplemental channels. A single supplemental channel can be shared among multiple terminals on a Time Division Multiple Access (TDMA) basis. The supplemental channel is allocated to a terminal for a certain period of time, generally in the range of a few tens of milliseconds, by a procedure called burst transmission.
The above-described resource allocation mechanisms, whether dedicated channels or dedicated time slices, are both essentially connection-oriented. Once a resource is allocated to a terminal, whether there is traffic to the terminal or not, the resource is always occupied by this terminal. While this makes user traffic identification simple, these designs are not optimal for internet packet applications.
High speed wireless internet access, through packet-based wireless access networks, is currently being developed. In a packet-based wireless access network, radio resources are dynamically allocated to users on packet-by-packet basis for increased system capacity. Such dynamic resource sharing on the forward link requires users to efficiently identify traffic directed to them. Typically, a user ID is used for this purpose. Each user packet is encapsulated in a radio link protocol (RLP) frame for the purpose of retransmission over a radio link. An appropriate user ID precedes each packet in the RLP frame, and is used by the terminals to identify their traffic.
One example of such a forward link traffic multiplexing format is shown in FIG. 1. User packets are encapsulated in RLP frames 50. The RLP frames 50 are then assembled into a forward link traffic multiplexing frame 52 with an appropriate user identification (ID) 54 preceding each RLP frame 50. The user IDs 54 are generally N-bit binary strings.
The forward link traffic multiplexing frame 52 is a layer 2 (L2) frame. The functions of L2 in a wireless access network are mainly resource management, traffic multiplexing and radio link quality improvement. As will be understood by those of skill in the art, some overhead including the user IDs 54 is introduced by L2, and this overhead occupies certain system resources. Clearly, more user traffic, as opposed to overhead, can be transmitted in each forward link traffic multiplexing frame if this overhead can be reduced.
This problem becomes especially acute as wireless internet access increases, and more services are provided by internet, such as stock information, weather forecasts, mobile location notices, etc. Such applications share common characteristics, such as very short packet sizes in the range of a few bytes, very bursty transmission, and delay insensitivity as compared to stream type applications. L2 control packets are also typically very short and quite bursty. For both these types of packets sent on a forward multiplexing channel, the user ID can account for significant percentage of the L2 frame.
It is, therefore, desirable to provide a method and frame structure that minimizes L2 overhead, such that more user traffic can be supported, thereby increasing system capacity and throughput.